This invention relates generally to heat regenerators; and specifically to magnetohydrodynamic air heaters operating cyclically at high temperatures and requiring some means for accommodating the resulting thermal expansion and contraction. The invention has particular application in coal-fired, open cycle magnetohydrodynamic power generation.
The function of a regenerative air heater in a direct coal-fired open cycle magnetohydrodynamic power generator is to extract heat directly from the exhaust of the magnetohydrodynamic channel and transfer this heat to the combustion air used to fire the coal combustor, thereby providing sufficient energy input to achieve high combustion temperatures as required for the generator.
The regenerative heater includes an inner chamber which is exposed to high temperature combustion gases which heat a cored brick matrix of refractory material. After the cored brick matrix has been sufficiently heated, the flow of combustion gases through the chamber is stopped, and air intended for combustion is pre-heated by directing it through the chamber and through the cored brick matrix from which it extracts heat. This heated air is then used to fire the coal combustor.
Designs for the support of the cored brick matrix should allow for efficient bottom flow removal and space utilization. The heater design should also be able to withstand the following adverse conditions:
Repeated sudden thermal shock during each cycle where the on-gas portion of the cycle operates at 2000.degree. F. gas temperatures and the on-air portion of the cycle operates at 1200.degree. F. air temperatures; PA0 Continuous bearing load due to the weight of the matrix which is near the material creep stress limits in the operating temperature range; and PA0 Continuous motion of the support system due to thermal expansion and contraction through the cyclic temperature range.
Various types of furnace designs have been proposed which concern problems experienced in the development of structures capable of withstanding high temperatures. Ordinary blast furnaces operate with a high temperature in the range 200.degree.-600.degree. F. and glass furnaces in the range 500.degree.-1500.degree. F. compared to the 2000.degree. to 2300.degree. F. expected with a magnetohydrodynamic regenerative air heater.